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Residential Sprinklers Required in the International Residential Code
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Issue 28: Residential Sprinklers Required in the International Residential Code

By Morgan J. Hurley, P.E.

Following years of attempts to require residential sprinklers in the International Residential Code,1 the 2009 edition will require residential sprinklers in all new one- and two-family homes and townhouses. The International Residential Code requires the installation of residential sprinklers in townhomes effective upon adoption of the code, and in one- and two-family homes effective January 1, 2011.

The United States differs from many countries in that fire safety codes and standards are not developed by the federal government. The U.S. Constitution leaves the development of building safety standards to the states. Most states do not write their own building safety standards; instead they use "model" codes that are written by private organizations. These "model" codes may be adopted in whole or with amendments by states and local jurisdictions.

The 2009 edition of the International Residential Code requires that residential sprinklers be installed in accordance with NFPA 13D or a simplified design procedure that is provided within the International Residential Code. NFPA 13D, Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes, contains requirements for the design and installation of sprinkler systems, such as discharge rates and installation criteria.

During the development of the 2009 edition of the International Residential Code (IRC), eleven proposals were submitted pertaining to residential sprinklers. Nine of these contained requirements for the installation of residential sprinkler systems, while two provided suggested simplified design criteria for residential sprinkler systems.


Two of the proposals would have required the installation of sprinklers in all new one- and two-family homes and townhouses effective upon the adoption of the code, while one proposal would have required sprinklers in all new one- and two- family homes and townhouses effective January 1, 2011. One proposal would have required sprinklers in all townhouses, but not in one- and two-family homes, while another would have required sprinklers in all townhouses and provided incentives for the installation of sprinklers in one- and two-family homes. One proposal would have required sprinklers in all new one- and two-family homes and townhouses that are made using lightweight construction (such as wooden I-beams or trusses) unless the lightweight construction was protected by a 30 minute barrier.

The other three proposals would have also provided incentives for the installation of sprinklers in one- and two- family homes and townhouses, but not require them. Ultimately, the IRC took differing approaches for one- and two-family homes and for townhouses so that local jurisdictions and the sprinkler installation industry could prepare for the requirement to take effect. These preparations might include training for sprinkler installers and training and certification for inspectors.

A 2007 study by the National Institute of Standards and Technology found that the benefits associated with residential sprinkler systems outweighed the costs.2 This study investigated the costs of installing sprinkler systems in three types of houses: one- and two-story freestanding single-family residences, and a townhouse. A multipurpose network system made using cross-linked polyethylene (PEX) tubing was selected for use to develop cost estimates, as it was found to be less expensive than other types of residential sprinkler systems.

These costs were compared with the expected benefits of having a residential sprinkler system, which included avoided deaths and injuries, avoided uninsured property losses, indirect costs, and reductions in homeowners' insurance premiums. Costs and benefits were compared using a common metric (dollars), and a sensitivity analysis was conducted.


Notarianni and Fischbeck3 also analyzed the costs and benefits of mandating residential sprinklers as a function of housing type (one- or two-family, multiple family or mobile home) community size, region of the country and whether the mandate would apply to new or existing homes. Notarianni and Fischbeck considered the installation costs, reduction in direct and indirect losses, reduction in injuries to occupants and fire fighters and the number of fire related fatalities that would be averted by installing residential sprinklers.

Notarianni and Fischbeck calculated with 90 percent confidence that the cost to society associated with a residential sprinkler mandate would be in the range of $4.2 million to $10.7 million per averted fire death, with a median value of $7.3 million (USD).

The City of Scottsdale, Arizona, was an early jurisdiction to require residential sprinklers, when it passed a residential sprinkler ordinance in 1985. Experience in Scottsdale over the 15 years following adoption of their residential sprinkler ordinance has shown that residential sprinkler systems reduced fire related property loss by an order of magnitude, and avoided 13 fatalities in a city with a population of just under 220,000.4

Prince George's County, Maryland, adopted a residential sprinkler ordinance in 1987. A study5 examining fires which occurred in structures from 1989 to 1999 found that 154 fatalities and approximately $40 million dollars (US) in property loss had been avoided during this almost 11 year period. (It is noteworthy that the losses investigated in this study were not limited to residential structures.)

Opponents to requiring residential sprinkler systems cited the potential damage from freezing pipes or accidental discharge, the unavailability of an adequate water supply in some areas among the reasons why residential sprinklers should not be required.

While the IRC has now been amended to require residential sprinklers in one- and two-family homes and townhouses, this does not mean that all future homes of these types will be equipped with residential sprinklers. The 2009 edition of the IRC must be adopted by local states and jurisdictions for this requirement to carry the force of law. The same organizations that opposed the requirement for residential sprinklers in the IRC development process have now shifted their efforts to local code adoption processes. Ultimately, legislative bodies within local states and jurisdictions will have the final say, and the result might be inconsistent approaches among U.S. states and jurisdictions.

Morgan Hurley is with the Society of Fire Protection Engineers.

  1. International Residential Code, International Code Council, Washington, D.C., 2009.
  2. Butry, D., Brown, M. H., and Fuller, S., "Benefit-Cost Analysis of Residential Fire Sprinkler Systems," NISTIR 7451, National Institute of Standards and Technology, Gaithersburg, MD, 2007.
  3. Notarianni, K., and Fischbeck, P., "A Methodology for the Quantitative Treatment of Variability and Uncertainty in Performance-Based Engineering Analysis and/or Decision Analysis with a Case Study in Residential Fire Sprinklers," Proceedings – 1998 Pacific Rim Conference and Second International Conference on Performance-Based Codes and Fire Safety Design Methods, Society of Fire Protection Engineers, Bethesda, MD, 1998.
  4. Ford, J., "15 Years of Built-in Automatic Fire Sprinklers: The Scottsdale Experience," Rural/Metro Fire Department, Scottsdale, AZ, (undated).
  5. Siarnicki, R., "Residential Sprinklers: One Community's Experience Twelve Years After Mandatory Implementation," Prince George's County Fire Department," 2001.

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